Wireless communication systems, including cellular phones, paging devices, personal communication services (PCS) devices, and wireless data networks, have become ubiquitous in society. The prices of end-user wireless devices, such as cell phones, pagers, PCS systems, and wireless modems, have been driven down to the point where these devices are affordable to nearly everyone and the price of a wireless device is only a small part of the total cost to the end-user. To continue to attract new customers, wireless service providers concentrate on reducing infrastructure costs and operating costs, and on increasing handset battery lifetime, while improving quality of service in order to make wireless services cheaper and better.
To maximize usage of the available bandwidth, a number of multiple access technologies have been implemented to allow more than one subscriber to communicate simultaneously with each base station (BS) in a wireless system. These multiple access technologies include time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA). These technologies assign each system subscriber to a specific traffic channel that transmits and receives subscriber voice/data signals via a selected time slot, a selected frequency, a selected unique code, or a combination thereof.
CDMA technology is used in wireless computer networks, paging (or wireless messaging) systems, and cellular telephony. In a CDMA system, mobile stations and other access terminals (e.g., pagers, cell phones, laptop PCs with wireless modems, and the like) and base stations transmit and receive data in assigned channels that correspond to specific unique codes. Conventionally, user voice and user data traffic are transmitted in traffic channels between a base station and a mobile station and network control signals used to set up and tear down a traffic channel are transmitted between a base station (BS) and a mobile station (MS) using control channels such as the paging channel and the access channel.
Channels that carry voice, data or control signals from the base station to the mobile station are referred to as forward channels and channels that carry voice, data or control signals from the mobile station to the base station are referred to as reverse channels. Most wireless voice services use a message flow comprising a page message from a base station to a mobile station, a page response message from the mobile station, and a traffic channel assignment message from the base station to the mobile station. In third generation CDMA systems that are currently being deployed, non-traffic channels are sometimes implemented as shared common control channels that can be configured to selectively perform paging and access functions.
Push applications use the above-described message flow in which a base station (BS) sends data to a mobile station (MS) and the mobile station acknowledges receipt of the message. Examples of push applications are subscriptions for delivery of headline news, stock quotes, weather, sports, and the like to a subscriber wireless device. Other examples include mobile station updates of MS diagnostics and updates of quality of service (QoS) parameters. To perform a push application, the base station sends a Data Burst message or a Feature Notification message on a forward common (shared) channel. If the Data Burst message requires an acknowledgment, the mobile station (MS) sends a MS Acknowledgment (ACK) Order message on a reverse common channel.
However, data services and other enhanced value-added services may over-utilize a common channel where there is a frequent need for common channel acknowledgment. Since the reverse common channel is not collision-free, multiple mobile stations may be accessing the common channels simultaneously. To ensure that the MS ACK Order message is received by the base station, the mobile station may use multiple access probes at gradually increasing power. The MS access probes start out on the reverse channel at a low power and the mobile station looks for a response from the base station after each re-transmission of the MS ACK Order message. This method of message acknowledgment increases latency, decreases system capacity and wastes power.
There is therefore a need in the art for an apparatus and related method for reliably sending an acknowledgment message between a base station and a mobile station. In particular, there is a need for systems and methods for transmitting MS ACK Order messages from a mobile station to a base station with minimum re-transmission of multiple access probes.